#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
int main()
{
	int m = 0, n = 0;
	double a = 0.0, b = 0.0, sum1 = 0.0, sum2 = 0.0;
	for (m = 1;m <= 100;m++)
	{
		if (m % 2 == 1)
		{
			a = 1.0 / m;
			sum1 = sum1 + a;
		}
	}
	for (n = 1;n <= 100;n++)
	{
		if (n % 2 == 0)
		{
			b = 1.0 / n;
			sum2 = sum2 + b;
		}
	}
	double result = sum1 - sum2;
	printf("%lf", result);
	return 0;
}